SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f068464d7ad4023a9053f88e615648da17f10cb9b9e63109748d998c2c2d6115' 
  AND token = '1zTFIWCTGtHgWzuP44eVWbkXIXFqtntTAPpVEBv/KnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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