SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6736b28f1a5aec09383153c4f08f80ea644ac898cece2cf579d0037734c844e6' 
  AND token = 'YRXj32xDntmf4op8RtEOPEo6YRPxXdAflHuk+LQfsO4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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