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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '103b28362ef61f44c4c76d3eb0ec9457f5f38546a0f3ff8b43936a8a49334637' 
  AND token = 'Tt71BQJYlklZH+BaHW2qJBRUob6v+rc1aEmBNjL6IzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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