SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f35943ff3845a781d1f2d096d90330ebe20557df896afe011d64af0b727d44a7' 
  AND token = 'dU8uUgUscmkYSiNWoObhhhXL/qoxUdjPPzpBKFvittI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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