SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5642557962f60a43ba1d918930f72f98b611431fdabfb9047e021f4969049a2' 
  AND token = 'uA9ZXfDgwfwcZEcDbkg4IvcC8Fq3DvzmzzFzij9tTBo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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