SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1870788cbab81082d9026e28deab170e8751c19e352a3786bb3f129fce870e5f' 
  AND token = 'nKCGj3CcTmWFeZxnvjVYuDG2RbwMDUMB6kz0q01qz7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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