SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1eb515636a47af4fe607419414c576e268e791b5ca38bc0a8a81afad494c973f' 
  AND token = 'Jg/8dj7yYbD2ulx6iw6d/7jz+zdqjGshLUE9Lmw9ujE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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