SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '249fce251e82e8899493f5e061815a4bf2435c7d5e09c0ee40341474d0b2809f' 
  AND token = 'J4m4u90b7S7AmFa8e6+Wz1LNjDOUuoWLCoYmB+zUzuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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