SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ea7783626647869a8fb4b595226e2797f2aa28f105b6d5c634159565bdfe257' 
  AND token = 'fsUJZlfoW1mLitmSW4SiEvcYQWnFjjilXQvstzQbT8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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