SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f421ff5606aee3b23994a799fb1e81040ae5cd57bfb1c75d988a0722878d4bdf' 
  AND token = 'EwHY9VfOVAeJxgnzVULymwlzyrKQk6ijyNChdvQIXcs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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