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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ddd51b2864d7bce9019a724f3ccd75d0708137a897a6622f1af40b46ffd6d40' 
  AND token = 'lx9V/DRF+Q8EcSGDcgUDR6Bxsf6UNuAM6MQDh0NGPaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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