SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3090759da985b105b639aa4bda14687b00fcbc7b05cfca33071efc49beabf2f' 
  AND token = 'PGekDcFuebimq5QFtjL8Cffs9Q8hRqjr+DfCw6rshLM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}