SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '854a5867a3569986f24cfb600fa2afc9916b60091f79964a177b828c0316076e' 
  AND token = 'uTU8BzEkZAx6UCtGGh0KdoGNL7yBYLmQ8zNczH/qUtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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