SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '999bef75cd1884dc0d3fa5ba6aaa1a99615c6d842da17e61a2da4143e426fc64' 
  AND token = '7p6NAr00OfFDiLgMU6rsUrUK5Ua9ohZKIa6gc3BOH14=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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