SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1339dc4e13b108b01c88caa3294e6f716f101314d0bee3d5331c27e501ec43f' 
  AND token = 'a9LCd1blLXczFWb3ZNlPYzpBPVMRqnTzVNco+mESXmg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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