SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6b6d4aec218521f64bdc79e80f43fe0052376abfda6743e9a25741f4b312502' 
  AND token = 'R5BZWP8aroSWcGh/67APltx0Jum8KqxOGR+UJXbj/JU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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