SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ada84cc22d1e800dd93dc2ce8a3f627ae94baadb4ccbdb60a4efb767229872a4' 
  AND token = 'XDMKYHZvykAqxGAl6hf7lK0OGRGfhiERZLxY4cUh3Rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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