SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20f7c1d63acacbd30130bddc547fe99702996d6ff9d13c2f7a9902a860ca5dfa' 
  AND token = 'MvUY/QY+wiSZr3jimeqqyfj6TlwELVVQZxQhyc7Jkf8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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