SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8e7db651f65f785f961604a16c7a754b93ef5ed313eb2b7a8b702d371552f87' 
  AND token = 'Eu6LRmv7vZIKqImPCa5AuhuFnV78jVZmJ+QJMdALYRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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