SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df47499231eddeb45c4cfec20be88f44ff3400b69509de7830e356de2033997b' 
  AND token = 'SxLzwkSQgldqpWKcyNKCHVU2kWDDlriMBbVjiRwNI88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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