SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c41ad5fe02767f5a264df662554fb629edbff53412b47a2112852325df4da48' 
  AND token = 'ghovFmhRojDZJr4HFSVE2lQUw2rPrDM4bk7EnjqbXFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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