SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca3809b8be57b39dcb4bfdc2245f197c7c68eec4d20ffc4a2a6372f6a167f699' 
  AND token = 'uMEE+oiLyZBXIzAwf+GoKOJ+Gf4HFGmkSoF8q8Vvrwg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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