SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78582bc2d252b8aa9be8c4f6eedf617d4987f3a88c75252957f2f78cb23b01a7' 
  AND token = '1EB+Sj4AhnWHmYy+4FV4FSBHA+xTz07glhuJszUdDjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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