SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff6c952b218b78900963bc6e6d4761972491d74db2f65e984747107798ddd713' 
  AND token = 'WefW1EjzHGZoniXzeDf7XaWYgNxHOfJZj2x51S0tKQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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