SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4649622111ee0410890035284b871ead3f5389df78d97675788c154da0760640' 
  AND token = '8ebLYHKjILfQzJxM8bO3PMAfKsu0yufjBejz0g6JTB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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