SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f549de19811bd922420328fb041463dc383991979a686d45acef338de92e7f9c' 
  AND token = 'E2X8pTdUEdptpL/xoiSwWbSBWbp2mIg/10BIz4tFsUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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