SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a7cd09dbaf59735068cf20772044be34f2e5ad69db221ad584ccf59663b88e0' 
  AND token = 'iPbFLXoFo784ZU4va84sTrEalm3zCmnG55ZnbFWgeug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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