SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7b02b88351e94d81910c716eb3667c63d32f52e61b33f0977b3c97818b7dbdad' 
  AND token = 'VBH+wZlQnse4UTcB8Pi6Ix25KsdSNI0sBBoumOsgPXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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