SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3704f7c4f0f7be3ab5cbd6c07f31173b1b7a46da0ce304e951a511f813cb0b7' 
  AND token = 'qdNmj6zcOeYvo3DgB/r4L0MkBmPgHTRZR5oo4NOW/5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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