SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbe139c6cc7aee403f1f242a3285e4755040fcbda8e6581c906f621adc31f096' 
  AND token = 'KM4iwzwJdYNoXQOltAQlB7dqXYSJj9f+92HcwULVywA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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