SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b727bb408cd15be602b72082e161f61f466509602f172c30ae401f779eeba3' 
  AND token = '4HwpSmjzH4sJCCYjMvygZgzP9iRCYQnG9V72wD7PYW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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