SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34920d7797db320701ad3725df999c9e1e2968843a4019174622f0141f746fec' 
  AND token = 'qONU7mlR8mQYcMrRIXx7yqNJfylvYo7QjnKPH07DrsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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