SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f850fd371a380b20482638dc22d9cd9753a35d36c3c9759cda0eb42695d1102' 
  AND token = 'hwNzU8Neq/lc3jyKZ0cSwDBArQrJDmE2OFlcOEz+xKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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