SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f689c34ecb1d0d7b21156d32d8f56a6890a45bfa93f25fccb3b1a24aaa85fb57' 
  AND token = 'E9oLfqVMvYNdWRWRQFRGG5hC6LsZO7b6/gFu0Cz1hdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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