SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9d54bdc1f763e76576b1de2cab2bfa43b42e901a94606e320da5cd54c7928ad' 
  AND token = 'xCRKMKEgMCZqOYoftvKSyKq0BZqgtwL8UINGRI2ZRlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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