SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '97fc27c3ec2a24fa4fc9ca39acef474a884b564f87268eea0135579786ab4d58' 
  AND token = 'BIVChZ+9k95wEwCE2DpGNwoIWdwKmnOkBLK+u/IsalE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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