SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d8fc6cd88e9f9184ab3d0a66ccafecb71feea21f9aa31a324d295577756a361' 
  AND token = 'Tytx1FeoDfv1EuzPTyD2MjErZwRgjQ6aBdrHL9QuH6k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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