SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f28657581c194123b6c07891da6b6178502e6d7402794242387833eea0847a8' 
  AND token = 'YN/QDC6bhtJgd0GOhxZnE5qvck+/+QbVPdBUnv+c+YI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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