SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21cf7094bc3a5e1c92c41edfad788f9604de1970a6f192bef782a1bce2957040' 
  AND token = 'md+C+PK9we4GeP9GOlCWCT1yMS8ebt++/qkiOZNuWUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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