SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'feca75f5b65b18850276819c4ee2cb6dd1850b301a492a483bdc02176592e390' 
  AND token = '+wurtPs2rBr+aM/kzcYxwVylY/VWMW6ShJlZFldCMUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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