SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37239d824532e4b9a83f0590d05c57a53a1ba8240b3f989ec80834ee149fcddb' 
  AND token = 'r1UvkPzFK4q0czZBXG77gUW+QEkLrpw3EJugYuaDxuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00070

JSON explain

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