SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99bf5c67667a5ff819a78ebde6f8a8ff95afac6db977adf5aa594d50fab5481f' 
  AND token = '9F4fcths2tcSLFkIbabJoxsTf3LxLIsk5FtD3+MWLqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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