SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6fcb1fc4dae9d89655007690005c634f31b79766ffc7a1917221b7fb8d364d4' 
  AND token = '/gx0BSys+kkrJgZUMHk2tPBAHAaZj1KTkZfHiMxAfKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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