SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2015860801d18d867bb199a96a01f739d00e78e50c4cdd573b66076a3ac40233' 
  AND token = 'ZSOA7QoagQVvQIX657EW/0Q5WgHbK537vDfDuHwkkOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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