SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6b15433d0164b21b8a05af2841072538f843adac25704f069599c51662278a6' 
  AND token = 'QqCb9zhxVWHktvfdZev7JMBy1Mmid+i7CFwDkEHV5nA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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