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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4376e68d0b95443f282cb6b3aa7dbdc98f397b16c9293bc8037c925b2edac8c' 
  AND token = 'fvSCGISnQSXHBHg0SAqSoBJBxBd46HEtQyMQtSyJuIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}