SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c31b7ed3d188dd1abaaf960ed2c64b6912c6892fc96c5a9056dcc07ffe39843' 
  AND token = 'qYklIOHs8aB6pWKmSs8Qf2a6zgvRvDJtLgLPWrXGvLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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