SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '755dbc2393ba46429213182aaad1ec5d3a9348b706ad10cfb94a62d1bbb042de' 
  AND token = 'ULr3oxveQ/CtzmSB8pWRz7hcpon6IaHWOVp7OtQzCZk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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