SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27d6c765102cfe95c3aac017dc9a4b85cc5b0c4941e63a0f5c04337ebbb848cc' 
  AND token = 'q1mWjZ0KZ3zf9LF9jgcwTkiEBD6dyC4p9IoMjKUmKnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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