SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ead39a533e4dc84ebb689356272881141679e935fd903183c8d6c9146f1eb698' 
  AND token = '+7oI+qSxeJi2jDWcaMwn23x/RvOfbSEzZ6GgN5QBIyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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