SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '620b6ec4f42f1bb6040b721001d92f25b4b2bee8afbf4fd48769459ea8096d36' 
  AND token = 'XCxKsDJ+nF5qru8Vvra+soIEuqY/H9chjFdbWsAdQJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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