SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58523fe9f9f1ff3fb0104ea784ced576680d6edcd54040d28b465044aa2ed67a' 
  AND token = '9ceYdQiwSnLd+suV67ivhp0Quc6s6AmS+ZYQbtVh9uA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}