SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d1a353c36cdd29574c61f37758e16c975839b3be3e364488e26fabdf2d52e82' 
  AND token = 'xyy5WrtEWkD2c0qavEZoEPPa7O0r0MjiTeFan1JSQeE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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