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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44689ef271f123c89f9addd50ddcc4104c52524dd766b8d08952c987e48a1feb' 
  AND token = '6PaQ773FWaFxpfqoPXGQP8feSp88JZNxglDs6CRbZas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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