SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71057f768a015b013c550b6384e2d4e29656c2a84dab27c541e0d881468c6ee8' 
  AND token = 'vp6oNKzZYGBMUXuyljurKcoeBktanwUl+EVS7n0Vhmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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