SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a005869374fff596673baa046b5208565dcac8d89670def3d88120c1ee1c8a5' 
  AND token = 'rAkULV0GdEoRp2TffMeZPN63WrBWz8mj9pB6XpqjDgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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