SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad99ef5d390ae5fb4724419d643a505f2378f4ed2c42fa5fd9fb69c618f89837' 
  AND token = 'wGUYUuj6WOFoLgmz3eYR6fcr2BfCa5hWa8tFLDGhvNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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