SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f594b8c59d5a011bcb2ff2866b516a75243c69ec558b0dfc232bfe9b65a29444' 
  AND token = 'dJmQD9jCg+TLpC7GLvuwVTtlyinEf+1QGraV6aAIGqQ=' 
  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"
    }
  }
}