SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '827351f824996b2feba19e0aed3b1e2966cb13750e78e67675400d731bf719f2' 
  AND token = 'fnmn9tzMRYXzK0YuR5CkdFY1/YEHdZXNtUo4MQRG65k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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