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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3874d1e8ba729e19c2b750d8ed8fddcf9b09f144f6e9dbf3a340c07a645042d' 
  AND token = '4N+OQd3FveKPaZ7HijYWtZ9G9W/ZtuAa7DI0ue6WZKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}