SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acce093467033410e28ce9c29a086bbf590331b17968155ed5bd09cba9d11ba0' 
  AND token = 'dAC86TrcZfEVoTkxInfiM7VjSPf+XV5BMBst1TjQEgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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