SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a519e453f591d19c2db21bccf761ec9c3bf2387388f63093350d62385b75714' 
  AND token = 'zNXjuauNsvjIsv8NULeHKu9mMLfdTPzkBZ4oqV1BgVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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