SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21371b8baf47a3ea1f5f8e1de4957cb3867f94738c9fef6dbcab69b8ca8909fa' 
  AND token = 'uqICzlweRXI2pkZPZAHRpzjBmzMkhtnJgXe6Q6lQn7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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