SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52d6ac4fbad4efb8b28958e5b2c59bf751d34b819295cd3a24bbce7973c2b2bd' 
  AND token = 'l6zbb2BSFzOTGJKYLo+YaJu4ezUwwHJGSaZ52CEZT04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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