SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a345e421699920411ec7e3c11925cd91b931bab047d16fdda9ad131176e5648' 
  AND token = 'RMOn5zn+WHywctS1IefOSol+bsOLJm1EZRqpAqss5Rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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