SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0938871caf50df1bc1770001464f5727c40eb110d23fdead4bab662d54e71a52' 
  AND token = 'fhJbrm2zZrcKGykz25eWdhM1yulaUmscgBp0qiAH3x8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}