SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f42ffeb6de75bfd36e9965a647fb5302ed07bb504d949e1ba8b69562341fd6' 
  AND token = 'kKuUUtCR9nqA166a+eY4maFcSPK1PeTmDGlKTsMu1b8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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